class Haml::Exec::Generic

def get_line(exception)
  # SyntaxErrors have weird line reporting
  # when there's trailing whitespace,
  # which there is for Haml documents.
  return exception.message.scan(/:(\d+)/).first.first if exception.is_a?(::SyntaxError)
  exception.backtrace[0].scan(/:(\d+)/).first.first
end

def initialize(args)
  @args = args
  @options = {}
end

def open_file(filename, flag = 'r')
  return if filename.nil?
  File.open(filename, flag)
end

def parse!
  begin
    @opts = OptionParser.new(&method(:set_opts))
    @opts.parse!(@args)
    process_result
    @options
  rescue Exception => e
    raise e if @options[:trace] || e.is_a?(SystemExit)
    $stderr.puts e.message
    exit 1
  end
  exit 0
end

def process_result
  input, output = @options[:input], @options[:output]
  input_file, output_file = if input
                              [nil, open_file(@args[0], 'w')]
                            else
                              @options[:filename] = @args[0]
                              [open_file(@args[0]), open_file(@args[1], 'w')]
                            end
  input  ||= input_file
  output ||= output_file
  input  ||= $stdin
  output ||= $stdout
  @options[:input], @options[:output] = input, output
end

def set_opts(opts)
  opts.on('-s', '--stdin', :NONE, 'Read input from standard input instead of an input file') do
    @options[:input] = $stdin
  end
  opts.on('--trace', :NONE, 'Show a full traceback on error') do
    @options[:trace] = true
  end
  opts.on_tail("-?", "-h", "--help", "Show this message") do
    puts opts
    exit
  end
  opts.on_tail("-v", "--version", "Print version") do
    puts("Haml #{::Haml.version[:string]}")
    exit
  end
end

def to_s
  @opts.to_s
end